Defensive Retractor: In Defensive Retractors, White and Black retract (take back) a given number of moves (-n moves), in order to reach a position in which a forward stipulation (e.g. #1, s#1) is met. Given a choice, Black will retract those moves that avoid or delay White’s goal. Unless otherwise stated, Black may defend by mating White through a forward move, if such an opportunity exists after one of Black’s retractions.The different kinds of Defensive Retractors only differ in the way uncaptures are handled, of course only legal uncaptures are allowed:

In Proca Retractors the retracting side decides, if and what man was uncaptured.

In Hoeg Retractors the opposite side decides, if and what man was uncaptured.

In Klan Retractors always White decides, if and what man was uncaptured.

In PacificRetractors there are no uncaptures at all.

Anti-Circe: Anti-Circe Calvet (the default type):After a capture the capturing piece (Ks included) must immediately be removed to its game array square (necessarily vacant, else the capture is illegal). R, B & S go to the square of the same colour as the capture; Ps stay on the file of capture; fairy pieces go to the promotion square of the file of capture. Anti-Circe Cheylan: As Anti-Circe Calvet except that captures on the rebirth square are not allowed.

Tries:1.pc3xBd4(pd2)? Bh8-d4+! 2.Kd2-e3 Re8-b8+! [while there is no doublecheck by K+R]1.Ke2-e3? Re8-b8+ 2.pb2xSc3(pc2) S~-c3+ 3.paxb(pb2) [closing the a-line] & 1.Rg1#but 2...Bg8-d5+ & 1.Qf3# forward defense!1.pb2xRc3(pc2)? Rc1-c3+! This retro species has become popular in the last 10 years by authors like Dittmann, Weeth, Thoma, Crisan and myself.

The problem is Co-tested with the program Pacemaker.In type Cheylan the wK doesn´t give check to the bK on e1 since this square is his own square of origin which is occupied. (Author)